Low literacy can lead to patient drug errors

February 19, 2007

The results of a new study indicate that lower literacy and a greater number of prescription medications can lead to the misinterpretation of the instructions on prescription drug labels. The study, "Literacy and misunderstanding prescription drug labels," was released on-line in November and published in the Dec. 19 issue of Annals of Internal Medicine.

Terry Davis, Ph.D., professor of medicine and pediatrics at the Louisiana State University Health Sciences Center in Shreveport and lead author of the study, explained that she and her colleagues gave 395 study participants five prescription bottles and asked them, How would you take this medicine? "We found that 46.3% of patients, regardless of their literacy level-low, marginal, and adequate-did not understand the instructions on at least one prescription label," she said.

"The majority of mistakes [51.8%] involved dosing," Davis said. She went on to say that these errors involved mistaking the abbreviation for teaspoon with that for tablespoon, so that patients were taking a tablespoonful of amoxicillin when they should be taking only a teaspoonful of the drug.

One of the most important findings of the study, Davis feels, was that patients of all literacy levels were better able to read the label instructions than to demonstrate the correct number of tablets to be taken. She reported that among those with low literacy levels (reading at a sixth-grade level and below), 70.7% were able to read the instructions, but only 34.7% were able to correctly demonstrate how many pills they should take.

"Another finding we did not anticipate was that the more medications patients were taking, the more likely they were to misunderstand the instructions," said Davis. "We found that those who were taking five or more medications daily were four times more likely to make a mistake with one of the prescription bottles they were shown."

Pharmacists can play a significant role in helping patients understand prescription drug labels and take their medications correctly, said Mark Middlebrooks, M.S., Pharm.D., director of pharmacy services for the LSU Health Sciences Center and the E. A. Conway Medical Center in Monroe, La. He urged pharmacists to talk with patients and address their questions and concerns.

Middlebrooks went on to say that "if patients do not understand the instructions on the label, often it is not even worth it for them to take their medication. But once patients find someone they feel is interested in helping them, they will spend the time to learn about their disease state and their medications."

Davis said, "When they pick up their prescription, people usually sign that they do not require counseling from the pharmacist. Our research indicates otherwise. Patients may even need to demonstrate back to you how to correctly dose the medication. The cool thing is that in the pharmacy, you have the medication right there!

"The bottom line is that prescription drug labels are seemingly simple, but not necessarily clear, and mistakes are common," Davis added. "This is important because, among other things, the population is aging, so the number of drugs being prescribed every year is increasing exponentially.

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